1959 BMW Isetta 300

Every year, swarms of America's wealthiest car collectors gather around Monterey, Calif. for the annual Pebble Beach Concours d'Elegance and all the car auctions that go with it. It's no surprise that some of the highest-priced collectible cars in the world are sold there.

But not all the cars for sale there are worth millions. Some of the coolest cars you'll find are the ones worth $50,000 or less. That's still not exactly cheap for a typical used car, but these are very special cars.

For instance, the BMW Isetta is one of the world's favorite affordable collectibles. Originally developed in Italy inanswer to outrageous post-war gas prices, the Isetta was built by BMW under license. While the Isetta flopped in Italy, where the Fiat 500 was more popular, it was a hit in war-ravaged Germany where its 50-plug-mpg fuel economy was especially appreciated.

The Isetta is likely to remain a collectible in the long run, too, according to experts at Hagerty Insurance, a company that specializes in insuring classic cars. Cute micro-cars like this are all the rage, as the recent successful auction of Bruce Weiner's huge collection of teeny cars showed.